Electronic Filters

Electronic filters are electronic circuits which perform signal processing functions, specifically intended to remove unwanted signal components and/or enhance wanted ones. These high-tech units, sometimes called electrostatic precipitators, are also incorporated into the ductwork. Electrostatic precipitators are the more common type of electronic air cleaner. As air passes through, a high-voltage current puts an electrical charge on particles.

At the other end of the unit, oppositely charged collector plates grab the particles like a magnet. Electronic filters work especially well on smoke particles too small to be trapped in media filters. Unlike media filters, electronic filters never need replacing, but the aluminum collector plates must be cleaned in soapy water every few months. The advantages of electronic filters are that they generally have low energy costs because of low pressure drop. The airflow through the units remains constant with use, and the precipitating cell is reusable, avoiding long-term filter replacement costs.

The major disadvantages are that (1) they become less efficient with use, (2) precipitating cells require frequent cleaning, (3) they can produce ozone, either as a by-product of use or intentionally, and (4) those installed into HVAC systems have a relatively high initial cost including expensive installation because of the size of the unit and its related wiring cost.